Method for forming an organic semiconductor film

ABSTRACT

A method for forming an organic semiconductor film, comprising applying to a base material a bicyclo compound and inducing a retro-Diels-Alder reaction in the bicyclo compound.

The present application is a divisional of application Ser. No.11/287,257, filed Nov. 28, 2005 now U.S. Pat. No. 7,211,120, whichapplication is a divisional of application Ser. No. 10/379,895, filedMar. 6, 2003 now U.S. Pat. No. 7,090,719, the entire contents of whichare incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a compound of which molecular structure andsolubility in a solvent can be changed by retro-Diels-Alder reaction anda method for producing the same. The present invention also relates toan ink for use in recording such as ink-jet recording, an ink cartridge,a recording unit, an ink-jet recording apparatus, a recording method anda recording medium. The present invention also relates to apattern-forming method for use in, for example, production of a DNA chipand a liquid composition used in the method. The present invention alsorelates to a method for detecting environmental history to detectwhether or not an object has undergone heating etc., and an article ofwhich environmental history is detectable.

2. Related Background Art

A technique for controlling the solubility of a compound in a solventaccording to the conditions has been strongly desired in varioustechnical fields.

For example, in the field of ink-jet recording, it is preferable, inview of the ink stability, that the coloring material in ink is in adissolved state, i.e., in a monomolecular state. On the other hand, inview of high quality image formation, when such an ink is once providedon a recording medium, it is preferable that the coloring material inthe ink is quickly separated from the solvent so that it can be retainedon the surface of the recording medium or in the vicinity thereof.So-called dye ink can satisfy the former requirement, and so-calledpigment ink the latter, but it is difficult to satisfy the both at thesame time. In recent years, there have been proposed various techniquesfor imparting characteristics of dyes to pigments by, for example,refining pigments or introducing water-dispersible functional groupsonto the surface of pigments, but there is still left great room forimprovement. Meanwhile, with the drastic improvement in performance ofink-jet printers, it has been proposed to use an ink-jet printer as anapparatus for producing devices having fine patterns, such as DNA chips.

SUMMARY OF THE INVENTION

As a result of intensive investigation based on the above technicalbackground, the inventors of this invention found that it is veryeffective for further development of ink jet recording technology todevelop a compound that maintains its solubility in a solvent when itexists in ink to give a stable ink but loses its solubility once it isprovided on a recording medium to remain on the surface of the recordingmedium or in the vicinity thereof, more particularly, a coloringcompound that can change its properties from those of a dye to those ofa pigment according to the situation in the ink-jet recording process.

Accordingly, one object of this invention is to provide a novel compoundof which solubility in a solvent is controllable and a method forpreparing the same.

Another object of this invention is to provide an ink which permitsrecording of high quality and imparts to an article a function ofdetecting the environmental history of the object which makes itpossible to know what environment the object has passed through.

Another object of this invention is to provide an ink-jet recordingapparatus, and an ink cartridge and a recording unit both of which canbe used in the apparatus.

Still another object of this invention is to provide a recording methodand a recording medium both permitting the production of a recordedarticle of high quality.

Another object of this invention is to provide a liquid compositionwhich can be used to permit recording of high quality as well as topermit imparting various functions to an article, such as anenvironmental history detecting function, which makes it possible toknow what environment the article has passed through, and a controllingfunction for controlling various properties which include: for example,the fastness, density and chroma of a recorded article and the responsecharacteristics and electric conductivity of a molecular deviceconstructed by recording.

Another object of this invention is to provide a pattern generatingmethod which permits accurate generation of a pattern as fine as nanometer order or pico meter order.

Still another object of this invention is to provide a method fordetecting the environmental history of an article and an article whichpermits such detection.

The present invention provides a compound which comprises asolvent-philic group which has an affinity to a solvent and makes thecompound soluble in the solvent, wherein the group is removed byretro-Diels-Alder reaction and removal of the group has the compound'ssolubility in the solvent lowered irreversibly.

Such a compound may have a tetraazaporphyrin skeleton.

Specifically, a compound having a tetraazaporphyrin skeleton ispreferably one having a structure represented by the following formula(I) or (II):

wherein R₁ and R₂ represent solvent-philic groups; M is a bi- totetravalent coordination metal atom; Y is a halogen atom, an oxygen atomor a hydroxyl group; and n is an integer of 0 to 2.

Otherwise, such a compound may have a porphyrin skeleton.

Specifically, a compound having a porphyrin skeleton is preferably onehaving a structure represented by the following formula (III) or (IV):

wherein R₁ and R₂ represent solvent-philic groups; M is a bi- totetravalent coordination metal atom; Y is a halogen atom, an oxygen atomor a hydroxyl group; and n is an integer of 0 to 2.

The present invention also provides a method for synthesizing a compoundhaving a tetraazaporphyrin skeleton that has a solvent-philic group fora solvent, where the solvent-philic group is removed byretro-Diels-Alder reaction. The method comprises the steps of:

(i) reacting a cyclohexadiene having a solvent-philic group for asolvent or a substituent group convertible into the solvent-philic groupwith a dicyano compound as a dienophile by Diels-Alder reaction to forma compound represented by the following formula (V),

wherein R₃ and R₄ represent independently a solvent-philic group or agroup convertible into a solvent-philic group, and

(ii) forming a tetraazaporphyrin skeleton by subjecting the compoundrepresented by the formula (V) to tetrameric cyclization and thencoordinating a metal atom into the tetraazaporphyrin skeleton.

Further, the present invention provides a method for synthesizing acompound having a porphyrin skeleton that has a solvent-philic group fora solvent, where the solvent-philic group is removed byretro-Diels-Alder reaction. The method comprises the steps of:

(i) reacting a cyclohexadiene having a solvent-philic group for thesolvent or a group convertible into the solvent-philic group as a dienwith a phenylsulfonyl compound as a dienophile by Diels-Alder reactionto form at least one of a compound represented by the following formula(VI) and a compound represented by the following formula (VII),

wherein R₃ and R₄ independently represent a solvent-philic group for thesolvent or a group convertible into a solvent-philic group;

(ii) subjecting at least one of the compound represented by the formulas(VI) and (VII) and an isonitrile compound of the formula CNCH₂COOR₅ (R₅represents a straight- or branched-chain alkyl group of 1 to 4 carbons)to cycloaddition reaction to form a compound represented by thefollowing formula (VIII),

wherein R₃, R₄ and R₅ are as defined above; and

(iii) forming a porphyrin skeleton by subjecting the compoundrepresented by the formula (VIII) to tetrameric cyclization and thencoordinating a metal atom into the porphyrin skeleton.

The present invention also provides an ink that comprises any one of thecompounds and a solvent described above.

The present invention also provides an ink that comprises any one of thecompounds described above and a solvent, and further comprises anothercompound as a coloring material.

The above ink is suitable for ink-jet printing.

The present invention also provides an ink cartridge that comprises anink container containing the ink described above.

The present invention also provides a recording unit that comprises anink container containing the above ink, and an ink-jet head for ejectingthe ink.

Further, the present invention provides an ink-jet recording apparatusthat comprises an ink container containing the above ink, and an ink-jethead for ejecting the ink.

The present invention provides a recording method that comprises thesteps of:

(i) applying an ink according described above to a recording medium; and

(ii) inducing retro-Diels-Alder reaction in the compound contained inthe ink provided on the recording medium.

The present invention also provides a liquid composition that comprisesa compound and a solvent described above.

The liquid composition is suitable as a composition to be ejected inink-jet printing.

Further, the present invention provides a method for pattern formationthat comprises the steps of:

(i) applying a liquid composition according to claim 22 to a basematerial site-selectively; and

(ii) inducing retro-Diels-Alder reaction in the compound contained inthe liquid composition provided on the base material to make thecompound insoluble in the solvent contained in the liquid composition.

The present invention also provides an article having on the surfacethereof one of the compounds described above or a reaction productresulting from retro-Diels-Alder reaction of the compound.

The present invention also provides a method for detecting anenvironmental history of an article having the above-described compoundon the surface thereof, the method comprises a step of detecting whetheror not the compound has been subjected to retro-Diels-Alder reaction.

The present invention also provides a recording medium which comprisesone of the compounds described above or a reaction product resultingfrom retro-Diels-Alder reaction of the compound.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a scheme of a method for synthesizing a porphyrin compoundaccording to this invention;

FIG. 2 is a scheme of a method for synthesizing a tetraazaporphyrincompound according to this invention; and

FIG. 3 is a schematic perspective view of an ink-jet printer accordingto this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Compounds According tothe Invention

A compound according to this invention has a group having an affinityfor a specified solvent (a solvent-philic group) and is soluble in thesolvent, and the sovlent-phlic group is removed from the molecule byretro-Diels-Alder reaction, leading to decrease in the solubility of thecompound in the solvent.

For example, when the solvent is water or a aqueous medium made of waterand a hydrophilic organic solvent (e.g. alcohols, glycols andglycerols), a solvent-philic group, in this case, a hydrophilic groupsuch as hydroxyl group, sulfonic acid group, carboxyl group and aminogroup, is introduced into a compound so that the solubility of thecompound in water (25° C.) is at least 1% by weight. When the compoundis subjected to retro-Diels-Alder reaction, the hydrophilic group isremoved from the molecule of the compound to lower the solubility of thecompound in the solvent as low as zero. The hydrophilic groups are notnecessarily limited to those described above, such as hydroxyl group andsulfonic acid group, but may be polar substituents including at leastany one of oxygen atom, nitrogen atom and sulfur atom.

When the specified solvent is an organic solvent insoluble or hardlysoluble in water, a lipophilic group such as alkyl groups and alkoxygroups, preferably alkyl groups or alkoxy groups with 4 or more carbonatoms, is introduced into a compound so that the solubility of thecompound in the solvent is at least 1% by weight. When the compound issubjected to retro-Diels-Alder reaction, the lipophilic group iseliminated from the molecule of the compound to lower the solubility ofthe compound in the water-insoluble or hardly soluble organic solvent aslow as zero.

In the following, the compounds according to this invention will bedescribed in further detail with examples.

Examples of a compound of which solubility in a solvent can beeffectively controlled by eliminating the solvent-philic group byretro-Diels-Alder reaction as described above include tetraazaporphyrincompounds represented by the following formula (I) or (II) and porphyrincompounds represented by the following formula (III) or (IV).

In the above formulae (I) to (IV), R₁, R₂ represent solvent-philicgroups respectively. When the solvent is aqueous, the solvent-philicgroup is preferably a polar group including at least any one of oxygen,nitrogen and sulfur, and the concrete examples of such polar groupsinclude, for example, hydroxyl group, sulfonic group, carboxyl group andamino group, among which hydroxyl group is more preferable. When thesolvent is an organic solvent insoluble or hardly soluble in water, thesolvent-philic group is preferably a lipophilic group including, forexample, alkyl groups such as methyl group, ethyl group, propyl groupand butyl group and alkoxy groups such as methoxy group, ethoxy groupand propoxy group, among which alkyl groups or alkoxy groups with 4 ormore carbon atoms are more preferable.

In the above formulae, M represents a divalent to tetravalentcoordination metal such as Zn, Cu, Fe, Mg, Al, Ga, Ti or Sn; Y is oneselected from halogen atoms such as chlorine, bromine and iodine, oxygenatom and hydroxyl group; and n is an integer of 0 to 2.

Compounds Having Porphyrin Skeleton with Water-Soluble Groups)

Next, described are concrete examples of porphyrin compounds of theabove formula (IV) of which solubility in water can be changed.

A porphyrin compound represented by the following structural formula(IX) has hydroxyl groups as a hydrophilic group and is soluble in anaqueous solvent due to the hydroxyl groups with a solubility in water at25° C. of 1 wt % or higher. When the hydroxyl groups are eliminated fromthe molecules of the compound by retro-Diels-Alder reaction, thesolubility of the compound in the aqueous solvent is lowered.

In general, porphyrin compounds are hardly insoluble in solvents, forexample, solubility in water at 25° C. of less than 1 wt %, because ofhigh flatness of porphyrin skeleton portion and π-π stacking. However,the porphyrin compound having the above formula (IX), wherebicyclo[2,2,2]octadiene skeletons with hydroxyl groups are condensed, issoluble in aqueous solvents due to the presence of bulkybicyclo[2,2,2]octadiene skeleton and hydroxyl groups. When the compoundof the above formula (IX) is subjected to retro-Diels-Alder reaction soas to eliminate the bridging ethylene moieties in the molecule, thecombined effect of the removal of hydroxy groups and stacking of themolecules due to the bulk reduction of the bicyclo[2,2,2]octadieneskeleton lowers the solubility in aqueous solvents, and the compoundbecomes insoluble or almost insoluble in, for example, water at 25° C.The above porphyrin compound represented by the formula (IX) is anexample of the compounds of the formula (IV) of this invention, wherethe central metal is zinc and the solvent-philic groups are hydroxylgroups, but the compounds of this invention are not limited to the aboveexample, and they may be appropriately selected from other porphyrincompounds, considering polarity in view of the solvent for which thecompounds should have affinity. As for the central metal, not only zincbut also copper, magnesium or aluminium may be selected properly so asto control the required electron state or the factors resulting from thestructure (e.g. absorption spectrum) of the compound, taking intoconsideration of ease of synthesis. Substituents convertible intosolvent-philic groups are not specifically limited, but in view of easysynthesis, hydroxyl group can be modified into ether or ester to attachvarious substituents such as long-chain alkyl and ethylene glycolgroups.

Method for Synthesizing Porphyrin Compounds

In the following the method for synthesizing a porphyrin compoundaccording to this invention will be described.

The compound according to this invention, which has a porphyrin skeletonand solvent-philic groups for a specified solvent and of whichsolvent-philic groups are eliminable by retro-Diels-Alder reaction, canbe synthesized in the following steps of:

-   (i) reacting a cyclohexadiene having a solvent-philic group or a    substituent group convertible to a solvent-philic group (a dien    compound) and a phenyl sulfonyl compound (a dienophile) by    Diels-Alder reaction to obtain at least one of the compounds of    formulas (VI) and (VII):

wherein R₃ and R₄ represent independently a solvent-philic group for thespecified solvent or a group convertible to a solvent-philic group;

-   (ii) subjecting at least one of the compounds of formulas (VI)    and (VII) and an isonitrile compound having the formula CNCH₂COOR₅    (R₅ represents a straight- or branched-chain alkyl group with 1 to 4    carbon atoms) to cycloaddition reaction to obtain the compound    having the following formula (VIII):

wherein R₅ represents a straight- or branched-chain alkyl group with 1to 4 carbon atoms; and

-   (iii) subjecting the compound represented by the above    formula (VIII) to tetrameric cyclization to form a porphyrin    skeleton and then coordinating a metal atom to the porphyrin    skeleton. In the above formulae (VI) and (VII), R₃ and R₄ may be the    same as R₁ and R₂ in the above formulae (I) to (IV), or may be    groups convertible to R₁ and R₂. The groups convertible to    solvent-philic groups include, for example, R₁ or R₂ protected with    a protecting group so as to prevent the reaction of R₁ or R₂ or both    during the synthesis process of porphyrin skeleton.

Now a synthesis method for the porphyrin compound of the above formula(IX) will be described in more detail. The compound can be synthesizedby the method shown in the scheme of FIG. 1. In FIG. 1, referencenumerals attached to the chemical formulae are to denote compounds ofthe formulae and small roman numerals attached to the arrows are todenote synthesis steps.

First, 3,5-cyclohexadiene-1,2-diol is reacted in the presence ofacetone, dimethoxypropane and p-toluenesulfonic acid to obtain acompound 2 of which hydroxyl groups are protected (step i). The compound2 and 2-nitro-1-phenylsulfonylethylene, as a dienophile, are subjectedto Diels-Alder reaction in the presence of toluene to obtain compounds3a and 3b (step ii) The resultant compounds 3a and 3b are dissolved indry THF (tetrahydrofuran) under nitrogen atmosphere, dry ethylisocyanoacetate is added on the ice bath, and dry1,8-diazabicyclo-[5,4,0]undecene-7 (hereinafter referred to as “DBU”) isadded and reacted by modified Barton-Zard reaction method to obtain acompound 4 as a precursor of the porphyrin compound (step iii).

The modified Barton-Zard reaction method used herein is a method forconstructing a wider variety of aromatic rings, which has beenestablished by improving a method for constructing a pyrrole skeletonfrom nitroalkene, an aromatic nitro compound and ethyl isocyanoacetate,as disclosed in J. Chem. Soc. Perkin Trans. 1, 1996, 417, by N. Ono, H.Hironaga, K. Ono, S. Kaneko, T. Murashima, T. Ueda, C. Tsukamura and T.Ogawa. The inventors used this reaction in combination with Diels-Alderreaction and successfully synthesized compounds having a novel function,which led to the completion of this invention. The Barton-Zard methodhas been known as a method for constructing an alkyl-substituted pyrroleskeleton. In this invention, however, the Barton-Zard method wasmodified to construct an aromatic-ring-substituted pigment precursor(aryl-substituted pigment precursor) of pyrrole skeleton. Specifically,the modified Barton-Zard method is used in the last step in the processof constructing a pyrrole ring where a sulfonyl compound or anitrosulfoyl compound having substituted solvent-philic groups issynthesized as a starting material through Diels-Alder reaction, andthen reacted with ethyl isocyanoacetate.

The compound 4 is dissolved in dry THF in a nitrogen atmosphere, andaluminium lithium hydride is added and reacted while icing the mixtureto obtain a compound 5 which is a tetramer of the compound 4 having aporphyrin skeleton (step iv). The compound together with a metal salt,such as zinc acetate, is dissolved in, for example, chloroform-methanoland reacted so that the metal is coordinately bonded to the porphyrinskeleton to obtain a compound 6 (step v). Then, the hydroxyl groups ofthe compound 6 is deprotected to give a compound 7 having the aboveformula (IX) (step vi). The solubility of the resultant compound 7 at25° C. is about 1.4 g in 1 g of methanol, about 2.55 g in 1 g ofisopropyl alcohol, and about 0.8 g in 1 g of a mixed solvent ofwater/isopropyl alcohol.

The compound 8 obtained by subjecting the compound 7 toretro-Diels-Alder reaction to remove hydroxyl groups therefrom is almostinsoluble in a aqueous solvent at 25° C.

(Diels-Alder Reaction and Retro-Diels-Alder Reaction)

Diels-Alder reaction is a reaction in which a compound having a doublebond or a triple bond is addition-bonded to the first and forthpositions of a conjugated double bonds to produce a six-memberedhydroaromatic ring. Retro-Diels-Alder reaction is a reverse reaction ofDiels-Alder reaction. For example, retro-Diels-Alder reaction of acompound having a fused ring portion of a bicyclo[2,2,2]octadieneskeleton removes ethylene at the bridging portion of the compound. Thus,the solubility of the compound can be controlled if the ethylene portionbears a group(s) that endow increased solubility in a solvent. Ifremoval of the ethylene portion by retro-Deals-Alder reaction accordingto the present invention leads to formation of a π conjugated system, itis preferable to design the original compound as such that the bulkystructure becomes flat as a result of the π conjugated systemconstruction, since such a molecular structure enables control of theagglomeration and association properties of the compound resulting fromretro-Diels-Alder reaction.

In order to realize the above preferred embodiment, it is preferable todeign such a system that the interaction between molecules increasesafter retro-Diels-Alder reaction due to hydrogen bond, van der Waalsforce, electrostatic force, polarity etc. Thus, even in a system wherethe association of a compound is too large to control in the prior art,if the properties of the compound before and after the retro-Diels-Alderreaction are properly designed, its agglomeration or associationproperties can be controlled effectively.

In the compounds of this invention, the substituents introduced at thebridging portion and removed by the retro-Diels-Alder reaction can behighly stable and safe. In other words, the reaction system can bedesigned so as not to cause a reversible or secondary reaction. It isgenerally known that Diels-Alder reaction between a diene compound and adienophile compound is a reversible reaction where an exothermicreaction (Diels-Alder reaction) and an endothermic reaction(retro-Diels-Alder reaction) are in an equilibrium state. JapanesePatent Application Laid-Open No. 11-349877 discloses an example oftaking advantage of this point to control the viscosity/temperature ofan ink-jet ink carrier. Since the reaction used in the above inventionis a reversible reaction, if the above reaction is applied to thepresent invention, cooling of a compound to decrease solubility mayinduce cyclization reaction again, causing increase in solubility of thecompound. Further, in the above invention, the diene compound anddienophile compound present after retro-Diels-Alder reaction areunstable, so that oxidation reaction may occur as a secondary reaction.Thus, the above invention is not suitable for the purpose of thisinvention. Japanese Patent Application Laid-Open No. 10-31275 disclosescontrol of polarity (solubility, cohesiveness) by using thedecomposition reaction of a triallylmethane compound by UV/heatapplication or by using a photo/thermo reversible compounds such as aphotochromic compound. Since the polarity-controlling portion used inthe above invention is a system that is decomposed by radical ioniccleavage so that an irreversible state can be achieved. However, theby-products of the reaction are instable and liable to induce anoxidation deterioration reaction, which may cause adverse effects.Further, since the photochromic reaction is a reversible reactioninduced by visible-/ultraviolet rays or heat, it is difficult to keep acertain state stably, so that it is not suitable for the purpose of thepresent invention.

Accordingly, in this invention, the reaction system is preferablydesigned as such that the products from a precursor by theretro-Diels-Alder reaction are not in a relationship of a diene and adienophile, between which Diels-Alder reaction may not occur. In oneembodiment of this invention, the compound removed by theretro-Diels-Alder reaction (1,2-ethylenediol) will not become adienophile. Further, 1,2-ethylenediol itself is an unstable compound andwill be oxidized to hydroxyacetaldehyde, so that no compounds that reactwith the water-insoluble compound 8 is present in the system, which hasbeen made water-insoluble. As a result, the retro-Diels-Alder reactionprogresses irreversibly. As described above, in order to allowretro-Diels-Alder reaction to progress irreversibly, it is preferable todesign the reaction system as such that the compound eliminated byretro-Diels-Alder reaction is converted, by oxidation, reduction orisomerization, into a compound which has no reactive double bond withwhich retro-Diels-Alder reaction will not occur.

Method for Retro-Diels-Alder Reaction

One way to cause retro-Diels-Alder reaction in a compound of thisinvention, e.g., the compound 7 in the scheme of FIG. 1, is to applyenergy by means of heating, irradiation of light, electromagnetic waveor radiation.

Compound Having Tetraazaporphyrin Skeleton with Hydrophilic Groups

Another example of the compounds of this invention is atetraazaporphyrin compound having the following structural formula (X).

The above compound maintains its solubility in aqueous solvents due tothe hydroxyl groups bonded to its bicyclo[2,2,2]octadiene skeleton andloses its good solubility in aqueouse solvents when ethylenediol issplit from the molecule by retro-Diels-Alder reaction, in the samemanner as with the compound of formula (IX).

Method for Synthesizing Tetraazaporphyrin Compounds

The method for synthesizing tetraazaporphyrin compounds of thisinvention will be described.

Compounds of this invention having a tetraazaporphyrin skeleton withsolvent-philic groups removable by retro-Diels-Alder reaction compoundscan be synthesized in the steps of:

-   (i) by reacting cyclohexadiene having solvent-philic groups or    substituents convertible into the solvent-philic groups and a    dicyano compound as a dienophile, by Diels-Alder reaction to obtain    a compound having the following formula (V):

wherein R₃ and R₄ independently represent solvent-philic groups orgroups convertible to the solvent-philic groups; and

-   (ii) forming a tetraazaporphyrin skeleton by tetrameric cyclization    of the compound of formula (V) and then coordinately bonding a metal    atom to the tetraazaporphyrin skeleton. In the above formula, R₃ and    R₄ represent the same groups as R₁ and R₂ in the above formulae (I)    to (IV), or groups convertible into these groups, for example, R₁    and R₂ protected with a protecting group so as to prevent the    reaction of these groups during the synthesis process of the    porphyrin compound.

Now the method for synthesizing the tetraazaporphyrin compound havingthe above formula (X) will be described in further detail. This compoundcan be synthesized by the method shown in the scheme of FIG. 2. First,3,5-cyclohexadien-1,2-diol is reacted in the presence of acetone,dimethoxypropane and p-toluenesulfonic acid to obtain a compound 2′ ofwhich hydroxyl groups are protected (step i′). The compound 2′ anddicyanoacetylene are reacted for Diels-Alder reaction in the presence oftoluene to obtain a dicyano compound 31 (step ii′). The resultantcompound 3′ and di-n-butoxymagnesium are dissolved in, for example,n-butanol under a nitrogen atmosphere and reacted to form a tetramer,that is, a tetraazaporphyrin skeleton while coordinately bonding themetal element to the tetraazaporphyrin skeleton, to obtain a compound 4′(step iii′). Then the compound 4′ is subjected to deprotection ofhydroxyl groups to obtain a compound 5′ having the above formula (X)(step iv′). The solubility of the resultant compound 5′ in water at 25°C. is about 50% by weight.

As shown in the step v′, a compound 6′ not having hydroxyl groupsobtained from the compound 5′ by retro-Diels-Alder reaction is insoluble(zero solubility) in water at 25° C.

Compounds with Oil-Philic Groups

While this invention has been described in terms of the compoundsexcellent in solubility in aqueous medium, it should be understood thatthe technique of this invention is not limited thereto, but it ispossible to lower solubility of an oil-soluble compound in hydrophobicsolvents by retro-Diels-Alder reaction. The examples of such compoundsinclude, for example, compounds having a structure represented by thefollowing formula (XI). These compounds can be easily obtained bymodifying the hydroxyl groups of the above-described compounds withhydrophobic groups such as alkyl group or by using a proper startingmaterial for synthesis.

Applications of Novel Compounds of the Invention

In the following a variety of applications of the above-describedcompounds will be described.

Ink

Since solubility of the compounds of the invention can be controlled asdescribed above, they can be used in ink to achieve high qualityprinting. Specifically, when a compound of the invention is used in anink as a coloring material, it is possible to change a dye-type coloringmaterial to a pigment-type coloring material. More specifically, if thecompound present in an ink in a dissolved state is applied on arecording medium and then subjected to retro-Diels-Alder reaction, thesolubility is lowered and the separation of the coloring material fromthe solvent occurs rapidly on the recording medium. According to thetechnique of this invention, if the compound (coloring material)resulting from retro-Diels-Alder reaction has a structure excellent infastness (including light fastness and gas fastness), both the superiorpoints of dye ink and pigment ink can be enjoyed. The coloring materialthat can be contained in the ink composition of of this invention is notspecifically limited but use of those having a strong associated statewith low solubility and dispersibility is very effective and thuspreferable. The suitable coloring materials include, for example,polycyclic coloring materials such as azo coloring materials, quinonedyes, quinacridon pigments; various chelate coloring materials; nitrocoloring materials; nitroso coloring materials; and aniline black. Thesecoloring materials are considered to have strong molecular interactionwith low solubility and dispersibility.

To be a compound (coloring material) excellent in durability (fastness),the compound must have such a structure that the molecular interactionallows the compound not affected by external deterioration factors(light, gas). Thus it is important to control the molecular interaction.

Ink-Jet Ink

An aqueous ink-jet ink can be obtained by using a water-soluble compoundof this invention, which is represented by the above formula (IX) or(X), as a coloring material.

The solvents used-for aqueous ink include, for example, water, and amixture of water and a water-soluble organic solvent. When a mixture ofwater and a water-soluble organic solvent is used, preferably thecontent of the water-soluble organic solvent is, not limited to, in therange of 3 to 50% by mass of the total mass of the ink. And preferablythe content of the water in ink is in the range of 50 to 95% by mass ofthe total mass of the ink.

The water-soluble organic solvents applicable include: for example,alkyl alcohols with 1 to 5 carbons, such as methyl alcohol, ethylalcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butylalcohol, tert-butyl alcohol, isobutylalcohol and n-pentanol; amides,such as dimethylformamide and dimethylacetamide; ketones orketoalcohols, such as acetone and diacetone alcohol; ethers, such astetrahydrofuran and dioxane; oxyethylene or oxypropylene copolymers,such as diethylene glycol, triethylene glycol, tetraethylene glycol,dipropylene glycol, tripropylene glycol, polyethylene glycol andpolypropylene glycol; alkylene glycols whose alkylene groups have 2 to 6carbons, such as ethylene glycol, propylene glycol, trimethylene glycol,triethylene glycol and 1,2,6-hexanetriol; glycerol; lower alkyl ethers,such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycolmonomethyl (or ethyl) ether and triethylene glycol monomethyl (or ethyl)ether; lower alkyl ethers of polyhydric alcohol, such as triethyleneglycol dimethyl (or ethyl) ether and tetraethylene glycol dimethyl (orethyl) ether; alkanolamines, such as monoethanolamine, diethanolamineand triethanolamine; sulfolane; N-methyl-2-pyrrolidone; 2-pyrrolidone;and 1,3-dimethyl-2-imidazolidinone. These water-soluble organic solventscan be used alone or as a mixture. Further, in order for the aqueous inkof this invention (ink whose solvent is aqueous solvent) to have desiredphysical properties, in addition to the above described ingredients,additives such as viscosity modifier, antifoamer, antiseptic agent,mildewproofing agent, surfactant and antioxidant can be added dependingon the situation.

Another Embodiment of Ink

While in the above-described inks, the compound of the present inventionis used as a coloring material, in the ink according to this invention,the compound of which solubility in the ink solvent is lowered byretro-Diels-Alder reaction is not necessary a coloring material. Forexample, the compound according to this invention can also be used as atleast one of the components of the ink. For example, when a compound ofthe invention of which solubility is changed by retro-Diels-Alderreaction is contained in the ink as a water soluble binder polymer, thepolymer that exists in a dissolved state in the ink becomes insoluble inwater by retro-Diels-Alder reaction after the ink was applied to therecording medium to give a recorded article of good water resistance,

Ink-Jet Recording Method

The aqueous ink containing a porphyrin compound having the above formula(IX) or a tetraazaporphyrin compound having the above formula (X) can besuitably used for ink-jet recording. Specifically, ink-jet recordingusing such an aqueous ink is performed in the steps of: for example,filling an ink tank of a commercially available on-demand type ink-jetprinter (e.g. BJ-F900 (trade name), manufactured by Canon) with the ink;mounting the ink tank on the printer and providing the ink onto arecording medium; and applying energy to the ink on the recording mediumto cause retro-Diels-Alder reaction. As the energy applied to the ink,heat, light, etc. can be used as already described. Preferred timing ofapplication of ink onto the recording medium and energy application tothe ink is, with a recording medium of good water permeability, is thatenergy is applied before the ink is fully absorbed in the recordingmedium; in more particular, when the recording medium is plain paper (PBpaper manufactured by Canon) of good water permeability, the time lagbetween ink application and energy application is about 1 second orless. Accordingly, in the ink-jet recording apparatus used for suchrecording, energy providing means may be provided very close to therecording head or next to the recording head so that providing ink onthe recording medium and applying energy to the ink can be performedalmost at the same time or with a time lag as short as possible.

Ink-Jet Recording Apparatus

A recording apparatus of this invention which includes a pre-heater anda halogen heater as means for causing retro-Diels-Alder reaction will bedescribed with reference to FIG. 3.

FIG. 3 is a schematic perspective view of a full-color serial-typeprinter comprising a changeable recording head (not shown in thefigure), and ink tanks C removably attached to the above recording head.The ink tanks C are one form of an ink container which contains the inkof this invention. The recording head and the ink tanks C are attachedto a carriage 3 in a detachable manner. The carriage 3 engages with aguide shaft 11 in its sliding direction along the shaft and is connectedto part of a driving belt 52 which is moved by a main scanning motor(not shown in the figure). This permits scanning by the recording headand ink tanks in the direction along the guide shaft. There existconveyer rollers 16 extending almost parallel to the guide shaft in theback of and in front of the recording area where recording is performedby the scanning recording head and ink cartridge. The conveyer rollers16 which also serve as a pre-heater, are driven by a control circuit anda subscanning motor (neither is shown in the figure) to heat therecording medium P and the novel compound of this invention contained inthe ink provided on the recording medium to induce retro-Diels-Alderreaction, while conveying the recording medium P. The recording medium Pbeing conveyed is subjected to main heating from the back of the printedportion at a platen part by a infrared heating heater unit 500 so thatthe recording medium P and the novel compound of this invention can beheated to a desired temperature to allow retro-Diels-Alder reaction toprogress rapidly. The infrared heater unit 500 comprises: for example, ahalogen heater 501; a net form platen 502 that prevents ingression ofthe recording medium and allows efficient heating; a reflecting platefor converging infrared light on the recording medium (not shown in thefigure); a sensor for sensing temperature changes (thermistor) (notshown in the figure); and a circuit for controlling the above sensor(not shown in the figure). While the heating means of the above ink-jetrecording apparatus was explained as infrared heating by using a halogenheater, the heating means can be another retro-Diels-Alder reactioninducing means, such as hot-air heating system and semiconductor laserfor photo-dissociation, depending on the retro-Diels-Alder reactionproperties of the novel compound of this invention.

Recording Unit

The recording unit according to this invention includes a recordinghead, an ink cartridge (ink container), a carriage device and a paperconveyance device, which are required for an ink-jet recordingapparatus, and in addition, an external energy providing device (e.g. aheating device, a light irradiating device or an electromagnetic waveirradiating device). A controller for sequentially controlling thesedevices and devices for ink recovering system are appropriately selectedand installed.

Ink Cartridge

The ink cartridge according to this invention is one selected from theink cartridges used in a common ink-jet recording system. Such inkcartridges include, for example, the following types: a type mounted onthe upper portion of a recording head so that ink can be fed to thehead; another type having a tube through which ink is fed to a recordinghead; and still another type integrated into a recording head.

Recording Medium

The above-described novel compound of this invention can be contained ina recording medium, for example, a recording medium used in ink-jetrecording. By using such a recording medium for ink-jet recording,ink-jet recorded articles of high quality can be obtained. One method tomake the recording medium contain the novel compound of this inventionis to coat the recording medium with the compound as a water-solublebinder. After recording is performed on such a recording medium with anaqueous ink, the water-soluble groups of the compound are removed byretro-Diels-Alder reaction to make the surface of the recording mediumhydrophobic. According to this operation, the degree to which theretro-Diels-Alder reaction progresses can be adjusted by controlling theenergy application to the recording medium, so that the degree ofhydrophobicity of the recording medium can be adjusted. Thus,satisfactory fixing and little bleeding of aqueous ink provided to therecording medium can be both accomplished at a higher level.

In this embodiment, the recording medium on which recording is carriedout is not specifically limited, and appropriately selected from therecording media applicable to the ink-jet recording methods usingaqueous ink. Such recording media include, for example, informationtransmitting sheets such as paper and film, fibers and leather. As tothe information transmitting sheets, those having treated surface, inmore particular, those having an ink-receiving layer provided on a basematerial, are preferable. The ink-receiving layer is provided byimpregnating or coating with a cationic polymer, or by coating withporous silica, alumina sol or special ceramic together with ahydrophilic polymer such as polyvinyl alcohol. It goes without sayingthat plain paper can be used as a recording medium.

Additives etc.

Various additives can be added to ink, liquid compositions, or recordingmedium. The examples of such additives include, not limited to,anti-oxidants represented by hindered amine and hindered phenol, andultraviolet absorbers represented by salicylic-acid compounds andbenzotriazole compounds. These additives are generally water-insoluble,and to be added in ink-jet recording ink or ink-jet recording medium,water-soluble substitutes (e.g. hydroxyl group, carboxyl group andsulfonic acid group) are usually introduced into the additives. In sucha case, however, migration (flowing-out) of the additives may occurunder the influence of moisture, for example, under a high humidity,lowering the effects of the additives. If the molecular weight of theadditive is increased to prevent migration, the solubility of theadditive will be lowered to affect the expected effect of the additive.Accordingly, use of the mechanism according to this invention, i.e.,elimination of soluble groups and structure conversion of a compound maycontrol the solubility of the additives to prevent migration; as aresult, the good solubility and migration prevention can be bothachieved. For this purpose, it is preferable to design the size,polarity and position of the groups to be removed from the precursor andto be remained on the product from the precursor.

Environmental History Detecting Method

As already described, one means for inducing retro-Diels-Alder reactionof the compound of the invention is heating. Thus, this nature of thecompounds can be used as means for detecting heat history of an article.Specifically, it is possible to design that the color of a compound willchange before and after retro-Diels-Alder reaction utilizing thestructural change of the compound, in particular, by construction of πconjugated system. Utilizing such change in color, it is possible todetect whether or not heat at a certain level or higher has been appliedto an article. For example, the compounds of this invention having aporphyrin skeleton or tetraazaporphyrin skeleton change color when theyare heated to a temperature equal to or higher than that will induceretro-Diels-Alder reaction. Although such a threshold temperature maydiffer depending on the compounds designed, with the novel compoundsdescribed above, color change is observed with heating at 120° C. orhigher. Accordingly, the heat history of an article can be appreciatedby attaching a compound of this invention to the article and observingwhether or not the color of the compound has changed due toretro-Diels-Alder reaction.

Method for Purifying Compounds

Compounds can be purified using the technique according to thisinvention. For example, various organic functional materials havingextended π electrons are considered useful. However, such compounds, forexample, tetraazaporphyrin compounds (e.g. phthalocyanine) are hard todissolve in solvents due to the molecular stacking, therefore, hard toremove impurities contained among the molecules for purification.However, using the technique of the present invention, it is possible tointroduce bulky bicyclooctadiene skeleton having hydrophilic groups toensure the solubility in a aqueous solvent in the synthesis ofphthalocyanine, to carry out purification by conventional procedure suchas filtration or extraction to remove impurities; and then removesubstituted ethylene group by retro-Diels-Alder reaction to allowextension of π electron system. Thus, a desired compound, aphthalocyanine compound of high purity can be easily obtained.

Pattern Forming Method

Retro-Diels-Alder reaction of the compounds of this invention enablesfilm formation of a compound having organic semiconductor properties. Itis generally known that anthracene, tetracene, polythiophene, porphyrin,and tetraazaporphyrin (e.g. phthalocyanine) compounds have organicsemiconductor properties. However, many of these compounds are hard todissolve in solvents because its π electron system has an expanded planestructure, as a result, a film of such a compound has been formed onlyby deposition. However, film formation by deposition has disadvantagesthat it is a batch method and has various limitation to the filmingconditions, and uniform film formation in a a large area is difficultand, moreover, it is costly.

The use of the technique according to this invention permits thecompounds of, for example, anthracene, tetracene, polythiophene,porphyrin, tetraazaporphyrin (e.g. phthalocyanine) to have solubility insolvents, and film can be formed from a solution of such a compound bycast-film process. After the film formation, ethylene group is removedby retro-Diels-Alder reaction from the compound of the film and the πelectron system in the molecule are expanded to obtain organicsemiconductor film of the desired compound. The film forming processesapplicable include, for example, cast-film process such as spin coatingor dip coating. In addition, with compounds such as anthracene,tetracene, polythiophene, porphyrin, and tetraazaporphyrin (e.g.phthalocyanine) compounds, screen printing and ink-jet printing are alsoapplicable. These film forming processes allow formation of film oflarge area at lower cost. If printing by ink-jet method is employed, inkcan be provided selectively at a desired position on a recording mediumwith a high accuracy, and a highly accurate pattern of an organicsemiconductor can be generated on the recording medium byretro-Diels-Alder reaction on the recording medium that makes thecompound insoluble in the solvent. Since the solubility of thesecompounds in solvents can be lowered only after the compounds areprovided on the base material (recording medium), the behavior of thesolvent on the recording medium and that of organic semiconductormaterial (herein mean the compounds, for example, anthracene, tetracene,polythiophene, porphyrin, tetraazaporphyrin (e.g. phthalocyanine)) canbe independent of each other. Specifically, even when the solventspreads on a base material in disorder, the organic semiconductormaterial that becomes insoluble to the solvent would not spread with thesolvent. This also contributes to the formation of patterns of higheraccuracy.

EXAMPLES

In the following the advantages of this invention will be furtherclarified by means of the examples based on this invention; however, itshould be understood that these examples are shown for illustrativepurposes only and are not intended to limit this invention.

Hereinafter the following abbreviations will be used.

-   THF: tetrahydrofuran-   DBU: 1,8-diazabicyclo-[5,4,0]undecene-7

Example 1 Synthesis of Porphyrin Compounds

A porphyrin compound of this invention having hydroxyl groups eliminableby retro-Diels-Alder reaction was synthesized as a coloring material inaccordance with the scheme shown in FIG. 1.

1.1. Synthesis of Compound 2

First a 20% solution of 3,5-cyclohexadien-1,2-diol (compound 1) in ethylacetate (25 ml) was prepared as a raw material, the solvent wasconcentrated under reduced pressure, and acetone (30 ml),2,2-dimethoxypropane (69 ml) and a trace amount of p-toluensulfonic acidwere added, followed by stirring at room temperature for 4 hours. Then a10% aqueous solution of sodium hydroxide (30 ml) and saturated brine (30ml) were added and stirred to stop the reaction, the reaction solutionwas extracted with diethyl ether (3×30 ml), the organic layer was washedwith saturated brine (3×30 ml), dried with sodium sulfate anhydride, andconcentrated under reduced pressure to obtain a compound 2,which is thecompound 1 with its hydroxyl groups protected, in a yield of 8.33 g.

1.2. Synthesis of Compound 3

The compound 2 (158 mg, 1.04 mmol) and2-nitro-1-(phenylsulfonyl)ethylene (230 mg, 1.08 mmol) were put into areactor, toluene (2.00 ml) was added, followed by stirring at 90° C. for3 hours. After the completion of the reaction, the reaction solution wasconcentrated under reduced pressure and column chromatographed (20 to30% by volume ethyl acetate/hexane), and the fractions of Rf 0.24 (20%by volume ethyl acetate/hexane) and Rf.0.18 (20% by volume ethylacetate/hexane) were concentrated. These concentrated fractions wererecrystallized to obtain compounds 3a and 3b in yields of 124 mg (0.339mmol, 32.6% by mass) and 62 mg (0.17 mmol, 16.3% by mass), respectively.

mp 151.9-152.6° C. ¹H NMR (solvent: CDCl₃) unit: δppm 7.87 (m, 2H), 7.71(m, 1H), 7. 59 (m, 2H), 6.16 (m, 2H), 4.81 (dd, J=5.6, 2.4 Hz, 1H), 4.33(dd, J=6.8, 2.9 Hz, 1H), 4.19 (dd, J=6.8, 2.9 Hz, 1H), 4.04 (dd, J=5.6,1.5 Hz, 1H), 3.70 (m, 1H), 3.48 (m, 1H) 1.28 (s, 3H), 1.22 (s, 3H) IR(KBr)/cm⁻¹ 2981 w, 1552 s, 1313 s, 1151 s, 1056 s, 727.0 m, 601.7 m.

1.3. Synthesis of Compound 4

365 mg (1 mmol) of compounds 3a, 3b(2,2-dimethyl-8-nitro-9-phenylsulfonyl-3a,4,7,7a-tetrahydro-4,7-ethano-1,3-benzodioxole)were put into a reactor, purged with nitrogen gas and dissolved in dryTHF (5.00 ml), and the reactor was immersed in an ice bath. After dryethyl isocyanoacetate (0.110 ml, 1.00 mmol) was added, DBU having beendistilled with calcium hydride (0.370 ml, 2.50 mmol) was added dropwiseover 5 minutes, and the ice bath was removed, followed by stirring atroom temperature for 17 hours. After the completion of the reaction, 2%hydrochloric acid (10.0 ml) was added, and the reaction solution wasextracted with ethyl acetate (3 ×20.0 ml ). The organic layer was washedwith saturated brine, dried with sodium sulfate anhydride, concentratedunder reduced pressure and silica gel column chromatographed (5% byvolume ethyl acetate/chloroform), and the fraction Rf 0.41 (5% by volumeethyl acetate/chloroform) was concentrated and recrystallized to obtaina compound 4 in a yield of 283 mg (97.8 mmol, 97.8% by weight).

mp 114.9-146.3° C. ¹H NMR (solvent: CDCl₃, unit: δppm) 8.58 (Br, 1H),6.68 (d, J=2.4 Hz, 1H), 6.50 (m, 2H), 4.56 (m, 1H) 4.34 (m, 2H), 4.32(q, J=7.0 Hz, 2H), 4.06 (m, 1H), 1.42 (s, 3H), 1.38 (t, J=7.0 Hz,3H), 1. 30 (s, 3H) IR (KBr)/cm⁻¹ 3345 s, 2892 w, 1681 s, 1297 m, 1141 s,1039 s.

1.4. Synthesis of Compound 5

The compound 4 (289 mg, 1.00 mmol) was put into a reactor purged withnitrogen gas and dissolved in dry THF (5.00 ml), and the reactor wasimmersed in an ice bath. Aluminium lithium hydride (114 mg, 3.00 mmol)was added and the ice bath was removed, followed by stirring at roomtemperature for one hour. After the completion of the reduction,saturated brine (20.0 ml) was added, the insolubles were Celitefiltrated, the reaction solution was extracted with chloroform (3×100ml) and dried with sodium sulfate hydride p-toluenesulfonic acid (80.0mg) was added to the solution, followed by stirring for one day.Further, chloranil (223 mg, 0.907 mmol) was added to the solution,followed by stirring for one day. After the completion of the reaction,the reaction solution was washed with an 1% aqueous solution of sodiumthiosulfate (50.0 ml) and saturated brine (50.0 ml), respectively, driedwith sodium sulfate anhydride, concentrated under reduced pressure, andcolumn chromatographed and recrystallized to obtain a compound 5 (in ayield of 39.8% by weight).

1.5. Synthesis of Compound 6

The compound 5 and copper acetate were put into a reactor, dissolved inchloroform (30 ml)—methanol (3 ml), followed by stirring at roomtemperature for 3 hours. After the completion of the reaction, thereaction solution was washed with water (100 ml×2) and saturated brine(40 ml), successively, dried with sodium sulfate anhydride, concentratedunder reduced pressure, and recrystallized from chloroform—methanol toobtain a reddish purple crystal (compound 6).

1.6. Synthesis of Compound 7

The resultant compound 5 was hydrolyzed in the presence of acid to besubjected to deprotecting, to obtain an intended water-soluble compound7.

Example 2 and Reference Example Preparation of Ink-Jet Recording Ink andImage Recording

Two types of ink-jet recording ink (aqueous ink) were prepared: oneusing the water-soluble compound 7,which was obtained in Example 1 anddesalted through an ultrafiltration membrane; and the other, as areference example, using phthalocyanine pigment (C.I. Direct Blue 199).

1) Desalted water-soluble compound 7 or C.I. Direct 5.0 parts     Blue199 2) Glycerol 5.0 parts 3) Urea 5.0 parts 4) Ethylene glycol 5.0 parts5) Water 80.0 parts Total 100.0 parts

Reddish purple color square patches of 1 cm×1 cm were printed on arecording medium (trade name: PR-101; manufactured by Canon Inc.) usingthe above two types of ink on an ink-jet printer, trade name: BJ-F 870;manufactured by Canon Inc. The color patches of Example 2 were heattreated at 120° C. for 1 minute for retro-Diels-Alder reaction of thecompound 7 and converted into cyan color patch. The resultant colorpatches of Example 2 and Reference Example were tested for theirlight-fastness, gas-fastness, water-fastness and moisture-fastness.

Light-Fastness

Light-exposure-fastness test was conducted with a xenone fade meter inaccordance with the following test conditions. This was to test fastnessof an image mimicking sunlight entering through a window in a room.

-   Test Conditions:-   Irradiation Intensity: 70 Kl×testing duration 520 hours-   Temperature/humidity conditions in a testing vessel: 24° C., 60% RH-   Filter: soda lime (outer), borosilicate (inner)

The light-fastness was evaluated as follows:

-   A: Density remaining rate of 90% or more-   B: Density remaining rate of 89 to 80%-   C: Density remaining rate of 79% or less

Gas-Fastness

Gas-exposure-fastness test was conducted with a gas corrosion testerunder the following test conditions (ANSI/ISA-S71.04-1985). This was totest fastness of an image assuming the effects of various gases in aroom.

-   Test Conditions:-   Exposing gas composition: H₂S: δppb, SO₂: 300 ppb, NO₂: 1250 ppb,    Cl₂: 10 ppb, O₃: 1200 ppb-   Testing duration: 72 hours, Temperature/humidity conditions in a    testing vessel: 24° C., 60% RH

The gas-fastness was evaluated as follows:

-   A: Density remaining rate of 90% or more-   B: Density remaining rate of 89 to 80%-   C: Density remaining rate of 79% or less

Water-Fastness

The obtained recorded article was immersed in city water for 5 minutes,drawn up from the water and dried, and its change in density before andafter the test was determined.

-   A: Density reduction rate of 1% or less-   B: Density reduction rate of 2 to 4%-   C: Density reduction rate of 5% or more

Humidity-Fastness

The obtained recorded article was stored in a thermo-hydrostat vessel at30° C., 80% RH for 1 week, drawn from the vessel and dried, and itschange in density before and after the test was determined.

-   A: Density reduction rate of 1% or less-   B: Density reduction ate of 2 to 4%-   C: Density reduction rate of 5% or more

The summarized results of the above tests for the compound 7 before andafter conversion by heating and the ink of the reference example (DirectBlue 199) are shown in Table 1.

TABLE 1 Example 2 Printed article Printed article Reference beforeconversion after conversion Example by heating by heating DBL-199Light-fastness B A A Gas-fastness C A C Water-fastness C A CHumidity-fastness B A B

As described above, the use of the recording method according to thisinvention permits ink to change from a solvent-soluble system to asolvent-insoluble system on a recording medium. By changing (lowering)the solubility of the coloring material on a recording medium,self-cohesion of the coloring materials is induced, endowing superiorfastness to recorded images. Further, the ink of this invention requiresno addition of polymer dispersing agent, unlike in the case of theconventional ink. Thus, according to this invention, advantages of theconventional dye ink and the conventional pigment ink are both given.

Example 3 Synthesis of Tetraazaporphyrin Compound

A compound of this invention having a tetraazaporphyrin skeleton wassynthesized in accordance with the scheme shown in FIG. 2.

3.1. Synthesis of Compound 2′

First, a 20% solution of 3,5-cyclohexadien-1,2-diol (compound 1′) inethyl acetate (25 ml) was prepared as a raw material, the solvent wasconcentrated under reduced pressure, and acetone (30 ml),2,2-dimethoxypropane (69 ml) and a trace amount of p-toluensulfonic acidwere added, followed by stirring at room temperature for 4 hours. Then a10% aqueous solution of sodium hydroxide (30 ml) and saturated brine (30ml) were added and stirred to stop the reaction, the reaction solutionwas extracted with diethyl ether (3 ×30 ml), the organic layer waswashed with saturated brine (3 ×30 ml), dried with sodium sulfateanhydride, and concentrated under reduced pressure to obtain a compound2,which is the compound 1′ with its hydroxyl groups protected, in ayield of 8.33 g.

3.2. Synthesis of Compound 3′

The compound 2′ (158 mg) and dicyanoacetylene (230 mg) were put into areactor, toluene (2.00 ml) was added, followed by stirring at 90° C. for3 hours. After the completion of the reaction, the reaction solution wasconcentrated under reduced pressure and column chromatographed (20-30%by volume ethyl acetate/hexane), and the fractions of Rf 0.24 (20% byvolume ethyl acetate/hexane) and Rf 0.18 (20% by volume ethylacetate/hexane) were concentrated. These concentrated fractions wererecrystallized to obtain a compound 3′ in yields of 184 mg.

mp: 151.9-152.6° C. ¹HNMR (solvent: CDCl₃ unit: δppm 7.87 (m, 2H), 7.71(m, 1H), 7. 59 (m, 2H), 6.16 (m, 2H), 4.81 (dd, J=5.6, 2.4 Hz, 1H), 4.33(dd, J=6.8, 2.9 Hz, 1H), 4.19 (dd, J=6.8, 2.9 Hz, 1H), 4.04 (dd, J=5.6,1.5 Hz, 1H), 3.70 (m, 1H), 3.48 (m, 1H) 1.28 (s, 3H), 1.22 (s, 3H) IR(KBr)/cm⁻¹ 2981 w, 1552 s, 1313 s, 1151 s, 1056 s, 727.0 m, 601.7 m.

3.3. Synthesis of Compound 4′

The compound 3 (365 mg) was put into a reactor purged with nitrogen gasand dissolved in dry THF (5.00 ml). Then a solution of n-butoxymagnesiumin n-butanol was added, stirred while heating at 150° C., to subject thecompound to tetrameric cyclization and metal complex. After thecompletion of the reaction, the reaction solution was extracted withethyl acetate (3×2.0.0 ml). The organic layer was washed with saturatedbrine, dried with sodium sulfate anhydride, concentrated under reducedpressure and silica gel column chromatographed (5% by. volume ethylacetate/chloroform), and the fraction Rf 0.41 (5% by volume ethylacetate/chloroform) was concentrated and recrystallized to obtain acompound 4′ in a yield of 283 mg.

mp 114.9-146.3° C. 1H NMR (solvent:CDCl₃ unit: δppm) 8.58 (Br, 1H), 6.68(d, J=2. 4 Hz, 1H), 6.50 (m, 2H), 4.56 (m, 1H) 4.34 (m, 2H), 4.32 (q,J=7.0 Hz, 2H), 4.06 (m, 1H) 1.42 (s, 3H), 1.38 (t, J=7.0 Hz, 3H), 1.30(s, 3H) IR (KBr)/cm⁻¹ 3345 s, 2892 w, 1681 s, 1297 m, 1141 s, 1039 s.

3.4. Synthesis of Compound 5′

The compound 4′ (289 mg) was put into a reactor purged with nitrogen gasand dissolved in THF (5.00 ml). 1 N hydrochloric acid (114 mg) was addedand stirred at room temperature for 1 hour. After the completion of thereaction, saturated brine (20.0 ml) was added, the reaction solution waswashed with 1% aqueous solution of sodium thiosulfate (50.0 ml) andsaturated brine (50.0 ml), respectively, dried with sodium sulfateanhydride, concentrated under reduced pressure, and columnchromatographed and recrysallized, to obtain water-solublephthalocyanine compound 5′ with its hydroxyl groups deblocked (in ayield of 39.8%).

According to this invention, two different properties: excellentsolubility in ink and fast solid-liquid separation after provided on arecording medium, are satisfied at a considerably high level, suchcompatibility has been considered difficult in the prior art.

This invention also enables the change in properties of a compound, forexample, conversion from a solvent-soluble system before patterning to asolvent-insoluble system after patterning. It enables dramaticimprovement in image fastness.

1. A method for forming an organic semiconductor film, comprising thesteps of: applying onto a base material at least a bicyclo compoundhaving a structure represented by formula

wherein M represents an element selected from Zn, Cu, Fe, Mg, Al, Ga, Tiand Sn; Y represents a halogen atom, an oxygen atom or a hydroxyl group;n is an integer of 0 to 2; and R1 and R2 represent a polar groupcontaining at least any one of an oxygen atom, a nitrogen atom and asulfur atom, or an alkyl group; and inducing retro-Diels-Alder reactionin the bicyclo compound.
 2. The method according to claim 1, wherein thepolar group is an alkoxy group.
 3. The method according to claim 1,wherein the retro-Diels-Alder reaction is induced by heating and lightirradiation.
 4. A method for forming a pattern of an organicsemiconductor film, comprising the steps of: applying a solutioncontaining at least a bicyclo compound to a desired position on a basematerial; and inducing a retro-Diels-Alder reaction in the bicyclocompound at a selected position on the base material to thereby form apattern of an organic semiconductor film having a size of nanometers atthe selected position, wherein the bicyclo compound has a structurerepresented by formula

wherein M represents an element selected from Zn, Cu, Fe, Mg, Al, Ga, Tiand Sn; Y represents a halogen atom, an oxygen atom or a hydroxyl group;n is an integer of 0 to 2; and R₁ and R₂ represent a polar groupcontaining at least any one of an oxygen atom, a nitrogen atom and asulfur atom, or an alkyl group.
 5. The method according to claim 4,wherein the polar group is an alkoxy group.